21120311021 has 4 divisors (see below), whose sum is σ = 21125060544. Its totient is φ = 21115561500.

The previous prime is 21120310997. The next prime is 21120311033. The reversal of 21120311021 is 12011302112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21120311021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21120310987 and 21120311005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120311221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2368085 + ... + 2376986.

It is an arithmetic number, because the mean of its divisors is an integer number (5281265136).

Almost surely, 2^21120311021 is an apocalyptic number.

It is an amenable number.

21120311021 is a deficient number, since it is larger than the sum of its proper divisors (4749523).

21120311021 is an equidigital number, since it uses as much as digits as its factorization.

21120311021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4749522.

The product of its (nonzero) digits is 24, while the sum is 14.

Adding to 21120311021 its reverse (12011302112), we get a palindrome (33131613133).

The spelling of 21120311021 in words is "twenty-one billion, one hundred twenty million, three hundred eleven thousand, twenty-one".